EP3234082B1 - Method for the extraction of oily components from coffee beans and/or of residual materials of coffee production - Google Patents

Description

The present invention relates to a process for the extraction of oily constituents from coffee beans and / or waste coffee production, which have a residual moisture content.

The current state of the art is that oil, especially vegetable oil, is recovered either by pressing or extraction. For this purpose, the oil-containing material is first dried and ground (conditioned) and then subjected to one or two successive methods. Usually, in the latter case, it is first pressed and then extracted. If it is high oil content materials, such as Rapeseed, presses has the advantage that it is technically relatively simple and sufficiently efficient to be used in a cost-effective and profitable manner. By pressing, up to 90% of the oil can be extracted from one material. Disadvantages are squeezed in addition to the oil and suspended solids, which is why the oil has to go through several purification steps.

The extraction of oil is usually carried out by means of hexane. The advantage of the extraction is the high efficiency and the purity of the oil. It can be recovered up to 98% of the oil, which is pure after the distillation of the extractant and normally requires no further treatment. The extraction of oil from plant materials with hexane as a solvent is currently the established industry standard and has two key aspects that directly affect oil yield and hence the efficiency and economics of the process. The first aspect is the solution efficiency, which describes how much oil per quantity of solvent and extraction material is accessible and can be dissolved in which time. This aspect is significantly influenced by the type of solvent, the composition of the oil, the working temperature, the conditioning of the oily material, the moisture content, and some other, less important factors. The second aspect is the withdrawal of the solvent-oil mixture (Miscella) from the extraction material. Ideally, at the end of the extraction, the material will no longer contain any oil and only pure solvent, which will be recovered in a subsequent step.

Technically, the extraction is made possible by extraction systems, which can range from the small Soxhlet attachment in the laboratory to industrial countercurrent systems. Of these, percolation plants are the most commonly used extractor for the extraction of oil. In percolation, a fluid flows through gravity through a porous one Material bed on a sieve bottom, a principle similar to the filtering of coffee. As the solvent (usually hexane) passes down through the bed of oleaginous material, the oil is dissolved in the solvent to form the miscella, which is collected below the sieve tray. As a rule, the systems are operated at light underpressure and close to the boiling point of hexane at 69 ° C for reasons of fire safety, so that the temperature-dependent solution and diffusion process take place as quickly as possible. With a suitable choice of the flake size, the residual moisture, the extractant and the temperature, a solution efficiency of 98-99% can be achieved here. This principle is common to all percolation plants, but due to the need to achieve sufficient withdrawal completeness and a certain material throughput, different variants of percolation extraction plants have arisen, which differ greatly according to manufacturer and application. Common to all of them is that the miscella with the highest oil content is always added to the extraction material at the beginning of the process, when its oil content is also highest. Successively, the miscella with a lower oil content is used to reduce the oil content of the extraction material step by step. The final step is to rinse with pure solvent that will cause the miscella with the lowest oil content to form during percolation through the material by taking up the least amount of oil. Subsequently, the extracted material is discharged and the extractant removed by steam distillation from the de-oiled extraction and recovered.

In the simplest form, the so-called batch plants, which are often found in laboratories and research facilities because of their low material throughput, such as. the SPX e & e Pilot Extraction Unit, the extraction material is placed in a well drained screen basket. The solvent is applied from the top and can percolate through the material. Due to the structure, the miscella can be withdrawn continuously. Alternatively, the extractor can also be flooded with solvent and withdrawn only after a certain residence time. In this version, separate rinses of the extraction material are used so that the rinsing effect of rinsing to rinse reduces the oil content of the miscella and of the extraction material. The number of possible flushes depends directly on the number and volume of the tanks, which are available for storage, the solvent and the miscella with different oil content. Depending on the design, it is also possible to remove the solvent directly from the extraction material in the extraction vessel without discharging, in which hot steam is introduced. Batch plants belong to the so-called deep bed plants.

To distinguish them from the so-called flat bed plants, which are designed for a continuous flow of material and are used accordingly in large plants come. The extraction material is applied here with a relatively small bed depth of 0.3 to 1.2 m thickness on a sieve plate, so that the top applied extraction agent can percolate through the material bed. The sieve bottom can be designed here as a conveyor belt and continue to move with the material or be designed as a groove. In this case, the extraction material is moved forward by screws or chain hoists. Below the sieve bottom is located in both versions a subdivided into sections collection container for the Miscella. The miscella is pumped from one section to the material of the following section and collected. The number of sections depends on the execution and material and is usually between four and twelve, with seven to eight sections occurring most frequently. In the first section of the Miscellatank, over which the fresh, just introduced material lies, is the miscella with the highest oil content, which is not used again for extraction, but for distillation and thus for oil extraction. In the last section, which is below the material, which is treated with fresh / pure solvent and then discharged, there is the miscella with the lowest oil content. The advantage of these systems is continuous operation. However, in comparison with batch systems, somewhat higher safety standards are necessary, since the removal of the solvent by steam distillation requires the removal of the hexane-containing, deoiled extraction material from the extractor.

Common to all industrially relevant methods is that the oil-containing material, such as oilseeds, oil crops and oil sands, should have a water content of less than 20%, better still less than 10%, and preferably around 7%, in order to efficiently recover the oil allow. If the water content during pressing is too high, mainly water and only a small proportion of oil is pressed out of the material. Similarly disadvantageous is a high water content in the oil extraction by means of hexane or other nonpolar solvent, such as gasoline or kerosene. If the water content is too high (> 10%), the water impedes the penetration of the hydrophobic solvent into the material and thus the solution of the oil. The recoverable oil content can sink to a no longer cost-covering measure, the oil production is uneconomical. For an economically interesting oil production by means of the mentioned methods, the water content must be reduced accordingly by dry storage or active drying. In particular, the active drying requires that considerable amounts of energy must be applied in order to dry the material to a suitable water content. This is always a relevant factor when the raw material has a high water content of more than 20% and tends by this water content for fermentation or fouling and thus unusable. This occurs especially with organic materials such as algae, freshly harvested oilseeds and oily waste materials of the food industry, such as for example, coffee reason, on.

If a material contains e.g. 30 wt .-% oil in the dry mass and has a water content of 55 wt .-% in the raw state, the following proportions result in one ton of wet material: 550 kg of water, 315 kg of base material and 135 kg of oil. In order to bring the material to a moisture level of 10%, 500 kg or half a ton of water would have to be evaporated. If this can not be achieved over long periods of storage, this must be done using energy, which can lead to considerable costs and can also have a negative impact on the quality of the oil due to oxidative stress. Since the enthalpy of vaporization of water is 2.26 MJ / kg, at least 1130 MJ (500 kg · 2.26 MJ / kg) is required to dry the material for which at least 28.25 kg of natural gas with a calorific value of 40 MJ / kg would have to be spent, which means a considerable effort and consumption of resources. One way of extracting oil from wet raw materials without prior drying and without costly special equipment is desirable in times of rising energy prices and increasing environmental awareness.

From the patents DD 229148 A1 of 1984 and US 8273248 B1 of 2012 There are known methods by which oil can be obtained from materials having a higher degree of moisture.

DD 229 148 A1 describes a process which allows a sufficiently efficient oil extraction with up to 20% water content in the material. This is achieved by pretreatment of the extraction material with alcohol or alcohol mixtures, wherein the amount of added alcohol should be between 5 to 7% of the water content in the extraction material. After treatment with alcohol followed by a simple extraction with hexane or another alkane or an alkane mixture (gasoline, kerosene).

US 8273248 B1 describes a method specifically for the extraction of oil from algae, which contains consecutive extraction steps after a drying step. First, reduce the water content and add alcohol or a mixture of alcohols to the algae. Subsequently, hexane, another alkane or an alkane mixture is added. The individual parts are then mixed together and left to rest. During the suspension of the mixture, there is a phase separation of the alkane phase and the water-alcohol phase, which are separated. From the phases oil and proteins can be obtained. For efficient extraction, the process must be repeated several times. Also for the in the patent US 8273248 B1 process called for special extraction plants, which have facilities for phase separation. Although both processes can produce oil from wet materials, either energy-intensive drying steps, multiple extraction and separation steps, or special equipment are still required. All these are factors which are high Cause costs and make the oil production unprofitable.

The patent WO 2012/138382 A1 discloses a method for the extraction of polar lipids from algae by the use of various extractants and in particular solvents with excess alcohol. In particular, no vegetable oils in terms of triglycerides (neutral lipids) and fatty acids are extracted from moist material, but polar lipids. Disadvantageously, dewatering and drying steps are an integral part of the process shown, while in the present invention these are excluded or reduced to a minimum.

In the EP 0617119A2 describes a method for the simultaneous extraction of hydrophobic triterpenoids such as azadirachtin and oil from the dry seed of the neem tree. Disadvantageously, only dry materials are extracted and the disclosed extraction solutions all have an excess of alcohol. The illustrated method is not optimized for the recovery of the oil but for the recovery of hydrophilic components.

Patent DE 69623762 T2 describes a method for obtaining terpenes, such as cafestolester, diethanol esters and isocafestol esters, by treating the coffee grounds with phosphoric acid and then extracting the terpenes. The disadvantage is that the coffee grounds must be dried before extraction. Extracted oil is called terpene soiling and should not be extracted from the coffee grounds.

US 2010/0287823 A1 discloses a method for obtaining biofuels from ground coffee. The coffee is first treated with water and then treated to obtain the triglycerides with an organic solvent such as methanol, ethanol, hexane or mixtures of organic solvents. In one embodiment, the water is separated from the ground coffee prior to extraction by, for example, freeze-drying or distillation.

The present invention has for its object to provide a simple, universally applicable, efficient, economical method for the extraction of oil-containing components from still moist coffee beans and / or moist residues of coffee production.

The object is achieved by a method for wet extraction of oily components from coffee beans and / or residues of coffee production, wherein the coffee beans and / or residues of the coffee production a residual moisture content of 10 to 95% by mass, particularly preferably from 30 to 85 Ma. %, very particularly preferably from 45 to 85% by mass, measured on the total mass of the coffee beans and / or residues of the Coffee production, extracted with an extractant mixture consisting of at least one polar and one nonpolar solvent and wherein the extractant mixture contains the at least one non-polar solvent in a proportion of 45 to 95% by volume, measured on the total volume of the extractant.

Extraction referred to in the context of the invention, the extraction of at least one substance from the extraction material coffee beans and / or residues of coffee production with a liquid extractant mixture. Moist extraction refers to an extraction in which still moist extraction material, with a residual moisture content, is used.

According to the invention, oil-containing constituents encompass all substances which can be extracted with the extractant mixture according to the invention from the extraction material coffee beans and / or residues of the coffee production. The oil-containing constituents are preferably fatty acid esters, in particular triglycerides and vegetable fats.

Coffee beans referred to in the context of the invention, all types of coffee beans, both roasted and unroasted and mixtures of these. The coffee beans may be pretreated, such as sorted or ground. Ground, un-extracted / brewed coffee beans are also referred to as ground coffee.

Residues of coffee production include according to the invention all types of residues (including coffee residues), both waste and by-products from the coffee industry. These include, for example, coffee grounds, ground coffee, separator and decanter sludge and mixtures thereof. Residuals are, for example, in the industrial Löskaffeeproduktion as well as in private households or catering.

The industrial production of Löskaffee essentially comprises the following steps, wherein the technical execution may vary in details depending on the company: The beans are roasted and ground into ground coffee. The ground coffee is then repeatedly extracted (scalded) by hot water and optionally under pressure, so that a coffee extract (also known as coffee) and a coffee base (brewed ground coffee) are produced. The coffee extract is then cleaned by decanters and separators of coffee grounds residues, remaining coffee grounds is referred to as separator and decanter sludge. Coffee extract residues are removed by means of belt presses or other techniques from the coffee grounds and returned to production after being cleaned by means of decanters and separators. Subsequently, the coffee extract is concentrated and freeze-dried or spray-dried, so that Löskaffeepulver arises. Coffee grounds, separator and decanter sludge are considered as waste in industry and sent for thermal recycling. Advantageously, they can be supplied to the inventive method due to their high water and oil content.

Coffee grounds according to the invention denotes the remnants of the coffee, in particular the coffee powder and / or ground coffee, after this has been subjected to a brewing process, for example. Coffee reason arises among other things with the drinking coffee preparation but also with the production of soluble coffee as a waste product.

Advantageously, mixtures of coffee beans and residues of coffee production can be used.

Residual moisture content according to the invention, the content of water, which is located in the coffee beans and / or the residues of coffee production.

Extractant mixture is a mixture of solvents that can be used to extract the oily components. Advantageously, the oil-containing components at least partially dissolve in the extractant mixture. After extraction, the extracted oily components are dissolved and / or undissolved in the extractant mixture. The extractant mixture consists of a polar and a nonpolar solvent. Solvents are classified according to their polarity (hydrophilicity). Polar and nonpolar in the context of the invention also refer to which solvent is the more polar or non-polar solvent when comparing two solvents. The Elutrope series provides information about this, for example.

The polar and nonpolar solvents are preferably immiscible with each other, but at least in the stated proportions by volume, miscible. Preferably, the polar solvent is miscible with the at least one oil-containing component to be extracted.

Preference is given to using as at least one nonpolar solvent, gasoline, kerosene, toluene, an alkane having a chain length of 5 to 25 carbon atoms or a mixture of these. Particularly preferred is an alkane having a chain length of 5 to 12 carbon atoms, most preferably selected from n-pentane, iso-pentane, iso-hexane, n-heptane, n-octane, even more preferably n-hexane used.

-Alkane is according to the invention saturated, acyclic hydrocarbons having the general formula C _n H _{2n + 2,} wherein n is an integer. The alkane can consist of both a linear carbon skeleton, as well as their isomers and branched carbon chains.

The polar solvent used is preferably an alcohol having a chain length of from 1 to 10 carbon atoms, more preferably from 1 to 6 carbon atoms, most preferably selected from methanol, ethanol, propanol, butanol and hexanol, more preferably 2-propanol.

According to the invention, the extractant mixture contains the nonpolar solvent from 45 to 95% by volume, more preferably from 55 to 85% by volume, most preferably from 55 to 75% by volume, even more preferably from 60% by volume, based on the total volume of extractant.

For the wet extraction fraction shown in this patent, mixtures of at least one polar and one non-polar solvent are used, usually an alkane and an alcohol. Suitable mixtures for the moist extraction shown here are mixtures with an alkane content of at least 50 wt .-%, preferably between 55 and 95 wt .-% and in particular between 55 wt% and 85 wt.%.

The extraction mixture preferably contains the at least one polar solvent in a proportion of 5 to 55% by volume, more preferably 15 to 45% by volume, very preferably 25 to 45% by volume, even more preferably 40% by volume. -%, measured on the total volume of the extractant.

The extraction mixture preferably contains further polar and / or non-polar solvents having a volume fraction of from 0.5 to 40% by volume, more preferably from 0.5 to 35% by volume, very particularly preferably from 0.5 to 19% by volume on the total volume of the extractant mixture. The other polar and / or non-polar solvents are selected from the polar and non-polar solvents according to the invention.

Alternatively, but not exclusively, binary, tertiary or higher mixtures of different alcohols such as methanol, ethanol, propanol and butanol, etc. can be used as the alcoholic phase and mixtures of pentane, hexane, heptane, gasoline or kerosene and the like as the alkane phase. But also mixtures based on acetone and toluene are possible.

When adjusting the mixture, care should be taken that the alcohol content is miscible both with water and with the alkane phase. If this is achieved, it is possible to extract moist materials directly, without drying or only a small amount of drying.

The extractant mixture is preferably used at a temperature above the ambient temperature but below the boiling point of the lowest-boiling solvent or the lowest-boiling azeotrope of the extractant mixture. An azeotrope is a mixture of at least two solvents whose vapor phase has the same composition as the liquid phase, whereby a distillative separation of the at least two solvents is not possible.

The efficiency of the extraction process increases as all chemical and physical processes with increasing temperature. The maximum working temperature corresponds to this Boiling point of the most volatile component of the extraction solution, which may also be an azeotrope of various components.

Advantageously, the temperature is chosen only so high that the oil-containing components to be extracted are not negatively changed by the applied heat.

Preference is given to a warm extractant mixture having a temperature of from 35 to 69.degree. C., very particularly preferably from 50 to 65.degree. C., very particularly preferably from 58 to 63.degree. Advantageously, the temperature is only slightly (0 to 6 ° C) below the boiling point of n-hexane (boiling point: 69 ° C).

Advantageously, the extraction rate is increased by the use of a warm extractant mixture, i. It can be removed with an extractant mixture with elevated temperature, a larger amount of oily ingredients than with the same volume of the same extractant mixture which has only ambient temperature.

Preferably coffee beans and / or residues of the coffee production are used with an average particle size of 0.001 to 10 mm, more preferably from 0.01 to 5 mm, most preferably from 0.01 to 2 mm. In a particular embodiment of the invention, the coffee beans and / or residues of coffee production to at least 30% by mass, measured on the total weight of the coffee beans and / or residues of coffee production, an average grain size of less than or equal to 2 mm.

Grain size in the context of the invention means the average size distribution of the particles within a batch of coffee beans and / or residues of coffee production.

For the efficiency of the process, it is advantageous if the oil-bearing material is as fine as possible. The smaller the particles of the oil-bearing material, the faster and more efficiently the extractant can penetrate and dissolve the oil. If the surface to volume ratio is too small, the extractant penetration will take too long and significant amounts of the extractant will remain in the material after the miscella has been withdrawn. Miscella refers to a mixture of an extraction (mixture) and at least one extracted oil.

Alternatively or in combination, the oil-bearing material may also be previously ground to obtain an optimum material size. The maximum particle size should be less than 5 mm and better still less than 2 mm. In particular, particle sizes below 1 mm are to be striven for, wherein at least 30% by weight of the oil-carrying material should have a particle size of less than 2 mm in the dry state.

Preference is given to coffee beans and / or residues of the coffee production with a content of oil-containing constituents of from 5 to 60% by mass in the dry mass (absolute tr.), Particularly preferably from 10 to 45% by mass. Tr., Most preferably from 15 to 35% by mass. Tr., Based on the total solids of the coffee beans and / or residues of coffee production used.

Total dry mass according to the invention denotes the total mass of the coffee beans and / or residues of the coffee production after its complete drying to constant mass.

Advantageously, 50 to 100% by mass, more preferably 65 to 99% by mass, most preferably 70 to 99% by mass of the oil-containing constituents, measured on the total mass of the coffee beans and / or the residues of the coffee production can be extracted.
Preferably, the oil-containing components are separated by distillation after extraction from the extractant mixture.
The separation of the extracted oil-containing constituents from the extractant mixture can be carried out, for example, over several stages, wherein first the most volatile component and then successively the less volatile constituents are separated off. Advantageously, an extractant mixture can be prepared from recovered solvent again.
Distillation of the miscella separates the oil from the solvent, as in a conventional extraction process based on hexane as extractant. By the distillation not only the oil is separated from the extraction solution, but it can also be the components of the extractant separated from each other. If these are collected in the same container and combined, the mixture can be used again as an extractant. If the individual components are separated, the extractant can be adapted to different properties of the material to be extracted during operation if the structure of the system permits this. Due to the different constituents of the extractant, the individual components have a different tendency to remain in the de-oiled base material. As a result, the proportionate composition of the extraction solution changes over time and the ratio of the components leaves the preset optimal range. Accordingly, it is necessary to regularly check the composition of the extraction mixture and readjust if necessary. This can be done for example by determining the density, but other methods such as fluorescence measurements are conceivable. Also, fluorescence measurements can be used to increase the oil content in the miscella control and determine when saturation is reached and the solvent must be renewed.
In a particular embodiment of the invention, mixtures of 50% by weight to 95% by weight of n-hexane and 5% by weight to 50% by weight of 2-propanol are used for extracting oily constituents from coffee beans and / or residues of coffee production used to dry without 70 - 98 wt .-% of the oil from materials (coffee beans and / or residues of coffee production) having a moisture content of 55 to 75 wt .-% and an oil content between 15 and 35 wt .-% in dry matter to win.
It is particularly preferable that the oil is also miscible with the alcoholic phase and, ideally, also soluble in it. If this is the case, it is possible to dissolve more than 90% of the oil from moist, oily material and to separate it from the extractant by means of distillation, as in a conventional extraction process with n-hexane as solvent.
In principle, the process of moist extraction can be run on all systems which are designed for hexane extraction, such as percolation and continuous belt systems. Only the distillation unit must be able to operate at higher temperatures than when using pure hexane, since the alcohols usually have higher boiling points than hexane. If necessary, seals must be used which are able to withstand both alkanes and alcohols. It should also be emphasized that colorants and suspended matter can be converted into the extract from the material, which normally can not be found in the oil in a pure hexane extraction. This is due to the alcohol content, which allows the transfer of hydrophilic substances to some extent. To remove these from the oil, another filter step can be integrated into the process, which allows to remove any suspended solids from the oil. The further treatment of the oil takes place after the separation of the solvent and the filtration in an oil refiner and is no longer part of this process. Also can be optimized by a reduction of the alcohol content of the process to a purer oil out, if thereby the extraction efficiency is not or only reasonably suffers.
Depending on the material, centrifuges or presses may be connected downstream in order to separate remaining extraction solution from the deoiled raw material.
Advantageously, current and initial investment costs are significantly reduced by the process according to the invention compared with the previously mentioned conventional and non-conventional extraction processes. The process of the invention thus provides a simple and universally applicable, efficient, economical process for the extraction of vegetable oils based on triglycerides from still moist materials, such as coffee beans and / or coffee production residues. Advantageously, the inventive method on all conventional extraction systems, if necessary with minimal modifications.
Surprisingly, it has been found that in an extractant mixture of polar and nonpolar solvents with a higher proportion of nonpolar solvent oily components such as triglycerides, regardless of the water content of plants such as coffee beans and / or residues of coffee production, extracted without drying in very good yields can be.
According to a particular embodiment of the invention, the coffee beans and / or remains of the coffee production are extracted several times with fresh extractant mixture. Preferably, the extraction is carried out one to 10 times, more preferably one to 7 times, most preferably one to 5 times, even more preferably three times. Advantageously, the degree of extraction is thus increased, ie more oily constituent is obtained from the coffee beans and / or residues of the coffee production. The individual extractant mixtures, which are obtained after a multiple extraction of the coffee beans and / or remnants of the coffee production with each fresh extractant mixture, are advantageously combined. From the combined extractant mixtures, the oily components are removed by distillation.
The present method essentially deals with a method for increasing the solution efficiency of the extraction of moist materials, which for the first time enables the efficient and cost-efficient extraction of moist materials without prior drying.

Based on the listed embodiments, the invention will be explained in more detail without limiting it to these.

Example 1 - Wet extraction with industrial coffee grounds

For extraction by means of binary extraction solutions, fresh, moist Robusta coffee base from the industrial dissolving coffee production with a water content of 68% and an oil content of 17.3% in the dry mass was used.

Portions of 27 and 28 g of moist coffee grounds each were placed in a filter with a pore size of 100 microns and placed in a beaker. The beakers were each filled with 100 ml of extraction solution composed of various mixtures of n-hexane and 2-propanol with volume fractions between 45:55 and 85:15 and a beaker of pure hexane. Both the mixtures and the pure hexane were heated to 60 ° C. The samples were left in the extraction solutions for 10 minutes and then removed. The samples were given an extra minute to drain. Subsequently, the obtained Miscellae were distilled and the oil obtained determined gravimetrically. The coffee grounds were also dried to determine the respective mass of the sample and thus to determine the maximum possible amount of oil to be extracted. This theoretical amount of oil and the amount of oil actually recovered were then put into proportion. By means of wet extraction, it was possible to obtain between 50 and 95% by mass of the oil, the yield being between 90 and 97% with an n-hexane content of 70 and 85% by volume. Beyond this optimum range, extraction efficiency dropped rapidly and was at 0% yield for pure n-hexane (100% by volume).

Example 2 - Wet extraction with decanter sludge from the Löskaffeeproduktion

For the wet extraction, fresh, moist decanter sludge from the Löskaffeeprodution was used with a water content of 75.4% and an oil content of 14.6% in the dry mass. The decanter sludge came from the industrial Löskaffeeproduktion. Portions of between 42 and 43 grams of wet decanter sludge were each placed in a beaker and dispersed in 48 to 49 grams of extraction solution at 60 ° C. The extraction solutions were various mixtures of n-hexane and 2-propanol with volume fractions between 45:55 and 70:30. The material remained in the extraction solutions for 20 min. The miscella were then filtered and distilled and determined the amount of oil obtained gravimetrically. By means of wet extraction, it was possible to obtain between 50 and 99% by mass of the oil from decanter sludge without drying.

Example 3 - Wet extraction with industrial arabica coffee base

Deep-frozen industrial Arabica coffee grounds with 60.4% residual moisture and an oil content of 31.2% i. Tr. examined. The coffee base was stored for thawing for 24 h in the refrigerator at 7 ° C for thawing. For the investigations, a 65:35 (n-hexane: 2-propanol) extraction solution was used. 50 g of coffee grounds were placed in a filter and placed in a beaker. The sample was poured with 100 ml extractant mixture, heated to 60 ° C, and allowed to rest for 15 min. Subsequently, the Miscella was withdrawn and rinsed three times with 30 ml of warm extractant mixture. It could be recovered in this way, 89% of the oil, while a test with warm n-hexane yielded less than 1%.

Claims (9)

1. Method for the wet extraction of oil-containing components from coffee beans and/or residual products of coffee production, wherein the coffee beans and/or residual products of coffee production, having a residual moisture content from 10 to 95 percent by mass, based on the total mass of the coffee beans and/or residual products of coffee production, are extracted by means of an extracting agent mixture consisting of at least one polar and at least one nonpolar solvent, and wherein the extracting agent mixture contains the at least one nonpolar solvent in a proportion of from 45 to 95 vol.%, based on the total volume of the extracting agent.
2. Method according to claim 1, characterised in that benzine, kerosene, toluene, an alkane having a chain length of from 5 to 25 carbon atoms, or a mixture thereof, is used as at least one nonpolar solvent.
3. Method according to either claim 1 or claim 2, characterised in that an alcohol having a chain length of from 1 to 10 carbon atoms is used as at least one polar solvent.
4. Method according to any of claims 1 to 3, characterised in that the extracting agent mixture contains the at least one polar solvent in a proportion of from 5 to 55 vol.%, based on the total volume of the extracting agent.
5. Method according to any of claims 1 to 4, characterised in that the extracting agent mixture contains additional polar and/or nonpolar solvents having a volume proportion of from 0.5 to 40 vol.% in total, based on the total volume of the extracting agent mixture.
6. Method according to any of claims 1 to 5, characterised in that the extracting agent mixture is used at a temperature above ambient temperature but below the boiling point of the solvent of the extracting agent mixture having the lowest boiling point or the azeotrope of the extracting agent mixture having the lowest boiling point.
7. Method according to any of claims 1 to 6, characterised in that coffee beans and/or residual products of coffee production having an average particle size of from 0.001 to 10 mm are used.
8. Method according to any of claims 1 to 7, characterised in that coffee beans and/or residual products of coffee production having a content of oil-containing components of from 5 to 60 percent by mass, based on the total dry weight of the coffee beans and/or residual products of coffee production, are used.
9. Method according to any of claims 1 to 8, characterised in that the oil-containing components are separated by distillation after being extracted by the extracting agent mixture.